This invention pertains to a method and apparatus for rearing shrimp and, in particular, to a method and apparatus for rearing post-larvae shrimp under controlled conditions.
In recent years attempts have been made to rear post-larvae shrimp under controlled conditions. Rearing shrimp in this manner has been carried out employing so-called intensive culture systems and methods.
Systems of this type have been proposed wherein the post-larvae shrimp are reared in a succession of units each being provided with habitat structures for the shrimp. U.S. Pat. No. 3,658,034 issued on Apr. 25, 1972 discloses one such system wherein the initial unit of the system comprises a tank provided with a habitat structure formed from a plurality of vertical substrates. Following this initial unit, are a number of further units which include tanks of increasing size and each of which is provided with a habitat structure formed from a number of cylindrical enclosures each for housing an individual shrimp. In this sytem, the tanks are disposed below one another so the shrimp content of a higher tank can be emptied into a lower tank when the shrimp in the higher hank have undergone a desired degree of growth. Moreover, in this system, the water in each tank is continuously circulated to remove contaminants therefrom.
Further U.S. patents which disclose intensive culture systems wherein vertically or horizontally aligned substrates provide habitats for post-larvae shrimp are as follows: U.S. Pat. Nos. 3,985,101 issued on July 2, 1975; 3,916,833 issued on Nov. 4, 1975; and 3,889,639 issued on June 17, 1975. In the last named patent, the intensive culture system disclosed comprises a plurality of horizontally arranged nets and a filtration system whose filter is backwashed by drainage of some of the water of the system. Moreover, in this system, light is directed through the central area of the nets to attract molting shrimp to such areas and thereby prevent these shrimp from being cannibalized by the remaining non-molting shrimp.
It is an object of the present invention to provide an improved system and method for rearing shrimp under controlled conditions on a commercial scale.
It is a further object of the present invention to provide a system and method for rearing shrimp wherein use of the rearing volume is maximized in a manner that does not contribute to shrimp mortality.
It is yet a further object of the present invention to provide a system and method for rearing shrimp wherein filtration of the rearing medium is carried out in an advantageous manner.